The aFGF is an acidic polypeptide hormone which is localized in brain, retina, neuron-related tissue, etc. and which has a molecular weight of about 16000. The aFGF exhibits growth promoting action on fibroblasts such as BALB/c 3T3 cells and the like, and on almost all mesoderm-derived cells (D. Gospodarowicz et al.; Endocrine Reviews, 8: 95 (1987)).
This aFGF also has neovascularizing activity. The neovascularizing activity of aFGF co-operative with its cell growth activity suggests the possibility of its use as agents for treating injured lesions and burns and for preventing and/or treating thrombosis, arteriosclerosis, and the like.
The natural type human aFGF is present in an extremely small amount among tissues or cells. Attempts to obtain this factor from human tissues have encountered serious difficulties arising from various limitations. Further, any quantitative assay for easily determining aFGF has not been established to date. Due to such significant difficulties, much fundamental information with regard to, for example, characteristics of aFGF, which are necessary for developing aFGF as a therapeutic agent, has not yet been uncovered.
If various fundamental information with regard to aFGF is obtained, for example, the in vivo distribution of aFGF and the system for its production, the development of aFGF as a drug will be accelerated. The quantitative determination of aFGF is important even upon the purification from recombinant products. Moreover, it is very important to trace aFGF level of blood in animals which are administered with aFGF; however, it is impossible to assay the concentration by the prior methods using 3T3 cells due to the comtamination of serum in a sample.
The determination of aFGF is usually achieved by culturing 3T3 cells under a reduced serum concentration, then adding aFGF to the 3T3 cells arrested in DNA synthesis, and calculating the aFGF concentration from the degree of recovery in DNA synthesizing activity thereby. This method has, however, several drawbacks including, requiring of delicate manipulations, the possibility of large errors in the aFGF determination and since the method requires the use of cells it is time-consuming.
Accordingly, there is a desire in the art for a simple means for the accurate determination of aFGF.
The present inventors made various investigations and studies to discover a practical means for aFGF protein determination. As a result, the inventors succeeded in preparing monoclonal antibodies against aFGF protein and capable of assaying the same. The present inventors have conducted further studies on the basis of this achievement and now developed the present invention.